Recently, a digital TV service using a wired or wireless communication network has come into wide use. The digital TV service may provide various services which cannot be provided by an existing analog broadcast service.
For example, an Internet protocol television (IPTV) service, which is a digital TV service, provides interactivity for enabling a user to actively select a type of a program to be viewed, a viewing time, etc. The IPTV service may provide various additional services, e.g., Internet search, home shopping, online games, etc. based on such interactivity.